Hayes and Garber - Cucurbit Breeding

CLASSIFICATION AND INHERITANCE OF SMALL GRAINS 95
and in F 2 the articulated basal types could easily be determined.
These occurred in a close approximation of the ratio of 1 articulated
base to 3 of the intermediate and saliva types (Fraser,
1919).
Open versus Side Panicle. Nilsson (1901) has used panicle
types and seed colors as a chief means of classification. The
distinction between the side and the open panicle is easily made,
but the various transitional open panicled forms are not easily
used in differentiation. Nilsson-Ehle (1908) has explained
crosses between an open-panicled and a side-panicled variety on
the basis of two main factor differences. Either factor when
homozygous or heterozygous produces open panicles. When
both factors are homozygous a variety with an open panicle and
drooping branches is obtained. When the factors are absent a
side panicle results. From crossing two open-panicled forms,
9-side forms were obtained out of a total of 112 plants.
These
side-panicled plants bred true while of the 103 open-panicled
plants, 24 again segregated giving both open- and side-panicled
forms. The parental varieties have panicles with erect branches
while a part of the open-panicled segregates have drooping
branches.
Resistance to Rust. Parker (1918) studied varietal resistance
of oats to stem rust, Puccinia graminis avence Erikss. and Henn.
and to crown rust, Puccinia lolii avence McAlpine. Crown rust
is a serious disease in the South while stem rust is more common
in the North. Several varieties of the red oat group of A.
sterilis including Burt, proved resistant to crown rust, while
certain side oat strains of A. saliva orienlalis belonging to the
White Russian group proved resistant to stem rust.
Studies, of the inheritance of resistance to crown rust under
greenhouse conditions, of crosses of Burt with Sixty Day, A.
saliva, showed segregation in F 2 .
Susceptible and resistant
plants, as well as various intermediates, were obtained (Parker,
1920).
A study of the inheritance of resistance to stem rust has
been made at the Minnesota Station (Garber, 1921). FI, F 2 ,
and F z crosses of resistant White Russian with two susceptible
varieties of A. saliva, Victory and Minota, have been grown.
The preliminary results show that for these crosses resistance is a
dominant character, the ratio in F 2 of resistant and susceptible
plants approximating 3:1. Susceptible F 2 plants bred true to